The present invention refers to an absorbent structure in an absorbent article such as a diaper, pant diaper, incontinence guard, sanitary napkin, dressing and the like.
Absorbent articles of the above mentioned kind are intended for the absorption of body liquids such as urine and blood. They usually have a liquid pervious topsheet, which during use is intended to be facing the wearer""s body and which for example consists of a nonwoven material of spunbond type. Further they have a liquid impervious backsheet, e g a plastic film or a hydrophobic nonwoven material, and an absorbent structure arranged between the liquid pervious topsheet and the liquid impervious backsheet. The absorbent structure may comprise more than one layer such as liquid acquisition layer, storage layer and distribution layer.
As an acquisition layer there is normally used a porous material with a high momentaneous liquid receiving capacity. Example of such materials are cellulosic fluff pulp of thermomechanic or chemothermomechanic (CTMP) type, chemically stiffened cellulosic fibers, fibrous waddings, carded fibrous webs, porous foam materials etc.
As a storage layer there is normally used cellulosic fluff pulp mixed with so called superabsorbents, i e crosslinked polymers with capacity to absorb body liquids several times their own weight (10 times or more). It is also possible to use an absorbent foam material as a storage layer. As a distribution layer there can be used cellulosic fluff pulp, tissue; layer, foam, synthetic fibers and the like having a high liquid distribution capability. It is also possible to combine two or more of the functions, acquisition, storage and distribution in the same layer.
In order to for example save space during storage and transports it is common to compress the absorbent articles strongly, which for materials with a low resiliency such as cellulosic fluff pulp, especially of chemical type, means that they maintain a high density also after they have been taken out from their package. This can in turn influence especially the liquid acquisition capacity negatively. It is therefore common to use a resilient material which can spring back as a liquid acquisition layer on top of a compressed absorbent core of cellulosic fluff pulp and superabsorbent.
EP-A-0 301 753 discloses an absorbent structure in the form of an open-cell foam material, which has been impregnated with a superabsorbent material. The superabsorbent material is retained in the foam by a binder. The preparation of the foam is made by dispersing the superabsorbent material in a solvent, after which the foam is impregnated with the dispersion and then the solvent is evaporated.
EP-A-0 160 572 discloses an absorbent structure comprising a carrier material applied in a fibrous structure. The carrier material can e g have a net-like structure and comprises a hydrophilic porous material, e g fibers or foam.
The object of the present invention is to provide an absorbent structure comprising a material with high spring back in dry as well as in wet condition and which besides has a high absorbent capacity. This has been achieved by the fact that the absorbent structure comprises a carrier material in the form of an open-cell foam containing hydrophilic fibers in its pore structure.
The hydrophilic fibers according to one embodiment at least partly are cellulosic fibers.
The foam material can in its pore structure further contain superabsorbent material.
The foam preferably has a relatively large pore size of no more than 15 and more preferably no more tan 10 pores per linear inch (no more than 6 and preferably no more than 4 pores per linear cm).
According to one embodiment the absorbent structure has a three-dimensional shape provided by heating and shaping of the foam material.
The invention firer refers to a method for manufacturing an absorbent structure in an absorbent article as above, at which hydrophilic fibers by means of a vacuum is sucked into an open-cell foam material.
Moreover it refers to an absorbent article such as a diaper, pant diaper, incontinence guard, sanitary napkin, bed protection, dressing and the like, which comprises an absorbent structure according to the invention. The absorbent structure can be arranged as a liquid acquisition layer, as a combined liquid acquisition- and storage layer or as a combined topsheet and liquid acquisition layer.